1. Field of Technology
The present invention relates to a governor that uses the viscosity of a fluid, and relates to a power generating device and to an apparatus that use the governor.
2. Description of Related Art
In order to keep an apparatus that uses an energy storage means, which stores, for example, the mechanical energy of a spring, the potential energy of a counterweight, or the thermal energy of heat accumulated in or extracted from a sealed bellows type container, as the drive power source operating at a constant speed, a governor is used to gradually release the stored energy.
The governor may be a mechanical governor or an electronically controlled governor.
An electronically controlled governor has a generator that is driven rotationally by stored energy and governs the rotational speed by electronically controlling rotation of the generator. Electronically controlled governors enable precise speed control, and are used, for example, to control driving the hour, minute, and second hands in a timepiece. See, for example, Japanese Unexamined Patent Application Publication H11-166980.
This type of electronically controlled governor requires a generator having a stator, coil, and rotor, and is therefore relatively large and relatively expensive. Mechanical governors may therefore be used instead depending upon the application.
Various types of mechanical governors are known from the literature and are widely used. See, for example, “Elements of precision devices II,” Richter, O. and Force, R. (Shoko Shuppan-sha K. K. (1958 Sep. 15, pp. 534-575); in Japanese) in which mechanical governors are classified in the following major groups.
(1) Brake-type Governors
(1-1) Brake-type Governors that use Solid Friction
FIG. 1568, FIG. 1569: governors that push a friction member against the inside circumference of a flange radially to the direction of rotation by means of centrifugal force
FIG. 1571: a governor that uses centrifugal force and a lever to push a friction member against the edge of a disk fixed on a shaft
FIG. 1572, FIG. 1574, FIG. 1575: governors that push the friction member of an oscillating pendulum against the inside circumference of a flange by means of centrifugal force
FIG. 1581, FIG. 1583: governors that push a friction member in the direction of the axis of rotation by bending a spring or link by means of centrifugal force
(1-2) Brake-type Governors that use Air Friction
FIG. 1596, FIG. 1597: governors that produce air resistance by spinning fan blades
FIG. 1598, FIG. 1599: governors that change the braking action by shifting the radial position of the fan blades or changing the blade angle
FIG. 1601: governors that automatically and outwardly shift the fan blades (in a direction away from an axis) by means of centrifugal force
FIG. 1603, FIG. 1604: governors that adjust by means of centrifugal force and wind pressure
(1-3) Brake-type Governors that use Eddy Current
FIG. 1606: governors that cause a conductive disk to rotate perpendicularly to the magnetic flux
(2) Escapement Type Governors
(2-1) Escapement Type Governors using Natural Vibration
FIG. 1607, FIG. 1608: governors with a gravity pendulum or spring pendulum
(2-2) Escapement Type Governors not using Natural Vibration
FIG. 1613, FIG. 1616, FIG. 1617: governors that use the inertial moment of a pallet fork
The following types of governors are used when the need for precision in the governor is relatively low.
In toys and other products for which sound output is acceptable, (1-1) brake-type governors that use solid friction and (2-2) escapement type governors that do not use natural vibration are used.
In small, inexpensive music boxes, (1-2) brake-type governors that use air friction are used, and (1-3) brake-type governors that use eddy current are used in electrical meters, for example.
In timepieces (mechanical timepieces) and other devices that require precision, (2-1) escapement type governors using natural vibration are used.
Examples of using the governors described above are also known from the literature, such as “Wristwatches of the World, No. 24” (World Photo Press K.K., Nov. 20, 1995 pp 69-73).
“Wristwatches of the World, No. 24” describes using (1-1) brake-type governors that use solid friction as the governor for the repeater (striker) mechanism of a timepiece and the sonnerie (striking mechanism).
A repeater strikes a gong or bell with a hammer to sound on demand when a button or slider is operated. A sonnerie strikes a gong or bell with a hammer to sound at a predetermined time (en passant), such as on the hour (0) and every quarter hour (15 minutes, 30 minutes, and 45 minutes). A dedicated spring is wound whenever the repeater is operated and at the predetermined timing of the sonnerie, but because the output torque of the spring varies according to the number of times the spring is wound, the interval at which the hammer strikes the gong varies according to the number of winds. The interval at which the gong is struck is shorter (faster) as the number of times the spring is wound increases (higher torque), and longer (slower) as the spring unwinds (torque decreases). The repeater or sonnerie indicates the time by the number of times the gong is struck, and the user may not be able to distinguish the strikes if the gong is struck too quickly, may miscount the strikes if the gong is struck too slowly, and may therefore not hear the correct time.
A governor such as described in (1-1) above is therefore used in repeater and sonnerie mechanisms in order to maintain a constant striking interval irrespective of how many times the spring is wound.
With the governor described in “Wristwatches of the World, No. 24,” centrifugal force produced by rotation of the rotor when the mechanism starts causes the weight and lever to move to the outside in resistance to the force of the spring pulling to the inside. As the speed of the rotor increases, part of the weight or lever contacts the inside wall of the cylindrical case surrounding the rotor. When the speed of the rotor drops due to this contact, the centrifugal force also decreases, and the spring pulls the weight or wing towards the rotational axis of the rotor. The inertial moment of the rotor therefore decreases, rotor speed rises again, and centrifugal force again causes the weight or lever to move to the outside.
As this operation repeats, the rotor turns at a substantially constant speed although minute fluctuations are visible.
The reason that a governor consisting of a balance, hairspring, pallet fork, and escape wheel for a timepiece is not used as the governor in a repeater or sonnerie mechanism is that the escapement and governor is large in size (particularly the horizontal size) and therefore not space efficient, costly, and requires so much energy to drive the hammer that a spring with low torque cannot be used. In addition, the speed increasing ratio must be low and the period of the balance must be short (fast) due to the required interval at which the hammer strikes the gong. More particularly, if the speed of the balance is increased approximately 100 times, a short hairspring must be used, wear on the shaft and striking portions is severe, and using such a governor is therefore not practical.